By now, more than eight years after the Sept. 11, 2001, attacks, we should be better at plucking a terrorist out of an airport security line. After all, we have some idea of what he’ll be like: young, socially alienated and deeply religious. And he’ll come from a country like Afghanistan, Algeria, Cuba, Iran, Iraq, Lebanon, Libya, Nigeria, Pakistan, Saudi Arabia, Somalia, Sudan, Syria or Yemen. (Under new Transportation Security Administration rules announced last weekend, people bearing passports from these 14 countries will undergo special scrutiny before boarding a plane.)

Or will he? What if he comes from Northern Virginia, like the five young men who were arrested in Pakistan on Dec. 8 and who have been accused of planning “terrorist activities,” according to Pakistani newspaper reports? The bottom line is that we can no longer assume that terrorists will come from any particular country or fit any particular profile. The more we learn about what makes people vulnerable to recruitment by terrorist organizations, the less any of the old generalizations hold up.

1: Most terrorists are spoiled rich kids.

Many prominent jihadists are indeed well off and well educated. Umar Farouk Abdulmutallab, the suspect in the failed Christmas Day airline bombing, comes from one of the wealthiest families in Nigeria. After the 2001 attacks, much was made of the engineering backgrounds of some of the hijackers, and Osama bin Laden famously hails from a wealthy family with close ties to the Saudi royals.

But terrorists come from all socioeconomic backgrounds. For poor people in countries where economic prospects are bleak, jihad can be one of the few jobs available.

Of the 25,000 insurgents and terrorism suspects detained by U.S. forces in Iraq as of 2007, nearly all were previously underemployed, according to Maj. Gen. Douglas Stone, the commander of detainee operations at the time. And according to Christopher Boucek of the Carnegie Endowment, the Saudi Interior Ministry found that most of the 639 convicted terrorists going through a rehabilitation program came from lower- or middle-class families, while 3 percent had high-income backgrounds.

2: Al-Qaida members come from repressive countries in the Middle East.

Al-Qaida’s core organization, which was responsible for the Sept. 11 strikes, is now based in Pakistan, but terrorist organizations claiming to be its affiliates include North Africa’s al-Qaida in the Islamic Maghreb, Jemaah Islamiah in Indonesia and al-Shabab, which is fighting in southern Somalia and has been recruiting Westerners.

The organization also has a more amorphous following of independent cells and individuals around the world. It is almost impossible to target or quantify this following because it isn’t centralized in any one location. Such self-made terrorists can be found anywhere, even in Fort Hood, Tex.

More broadly, there is no particular political system that reliably promotes or deters terrorism. And democracy is not the cure-all it is often assumed to be. There are many more terrorist incidents in democratic India, for example, than in non-democratic China or Saudi Arabia. (This may be because authoritarian regimes are good at controlling terrorism within their borders.) And economist Alberto Abadie of Harvard University has found that the transition to democracy can be a particularly dangerous period with regard to terrorism — consider the experiences of Spain in the late 1970s, Russia after the fall of communism and Iraq today. Failed and failing states, such as Yemen and Somalia, also make particularly fertile ground for terrorism.

3: Al-Qaida is made up of religious zealots.

To the contrary, rank-and-file terrorists who claim to be motivated by religious ideology often turn out to be ignorant about Islam. The Saudi Interior Ministry has questioned thousands of terrorists in custody about why they turned to violence, and found that the majority did not have much formal religious instruction and had only a limited understanding of Islam. According to Saudi officials, one-quarter of the participants in a rehabilitation program for former jihadis had criminal histories, often for drug-related offenses, whereas only 5 percent had been prayer leaders or had other formal religious roles.

In the Netherlands and elsewhere in Europe, second- and third-generation Muslim youths are rebelling against what they consider the culturally contaminated Islam that their parents practice and that is promoted in their local mosques, favoring instead the allegedly purer Islam that they discover online or via imams from the Middle East. But the form of Islam they turn to is often highly unorthodox. For example, the Hofstad group in the Netherlands — a network of radicalized young Muslims — practiced a sort of do-it-yourself Islam cobbled together from Web sites and the teachings of a self-taught Syrian imam who is also a former drug dealer.

And groups linked to al-Qaida, including in Somalia, have been begun using anti-American hip-hop music or “jihad rap” in their recruitment videos, even though such music is considered counter to the extremist version of Islam promoted by the terror network. Rather than Islam leading young recruits toward al-Qaida, it may be an ignorance of Islam that renders youths vulnerable to al-Qaida’s violent ideology.

4: Terrorists are motivated by a strong belief in their cause.

Terrorist movements often arise in reaction to a perceived injustice, whether real or imagined. Yet ideology is not the only, or even the most important, factor in an individual’s decision to join. In my research and interviews with terrorists, I have found that operatives are often more interested in adopting a new identity than in supporting a terrorist group’s stated goals. Many speak, in particular, about being motivated by a feeling of humiliation. A Kashmiri militant founded his group because, he said, “Muslims have been overpowered by the West. Our ego hurts … we are not able to live up to our own standards for ourselves.”

The reasons that some people become terrorists are as varied as the reasons that others choose conventional professions: market conditions, social networks, contact with recruiters, education and individual preferences. And just as the passion for justice that may animate a young law student is not necessarily what keeps him working long hours at a law firm while hoping to make partner, a terrorist’s motivations for staying with his cause can also change.

Most terrorist groups disappear quickly; those that survive tend to have the sort of flexible ideology that can attract a diverse array of recruits and funders. Al-Qaida is among the most disciplined terrorist groups, but its goals and its list of enemies are constantly shifting. Documents analyzed by scholars at the Combating Terrorism Center at the U.S. Military Academy reveal an astonishing lack of clarity about the group’s purpose, even among leaders of the organization. Abu’l-Walid, a leading strategic thinker for al-Qaida, has complained about constantly shifting strategic goals, lamenting that “waging jihad like a rhinoceros is stupid and futile.”

5: The typical terrorist recruit is an alienated loner.

According to The Washington Post, Abdulmutallab, the alleged Christmas airplane attacker, wrote in an online Islamic forum: “I have no one … to consult, no one to support me and I feel depressed and lonely. I do not know what to do. And then I think this loneliness leads me to other problems.”

But for most terrorist recruits, the problem isn’t so much a lack of friends as the wrong friends. This dynamic isn’t so different from the way gang recruiting works in the United States: Terrorists often join an armed struggle because they have a buddy who has done so. In a survey of 516 Guantanamo detainees, researchers at the Combating Terrorism Center found that knowing another member of al-Qaida was a better predictor of who became a terrorist than was belief in the idea of jihad.

It is interesting to note that in its rehabilitation efforts, the Saudi government tries to compete with convicts’ ties to terrorism networks by reconnecting them to their families and home communities, and most controversially, by trying to find wives for the former fighters.

Ultimately, some individuals may join terrorist groups out of a misplaced desire to transform society. But over time, the social and psychological rewards of belonging can eclipse such motivations. Terrorists want to better their own circumstances at least as much as they want to change the world.

Jessica Stern serves on the Hoover Institution Task Force on National Security and Law and is a lecturer at Harvard Law School. She is the author of “Terror in the Name of God: Why Religious Militants Kill.” She wrote this column for the Washington Post.

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